The present invention relates to fabrication of articles, and in particular, fabrication of articles using a sequential layering technique.
Recently, three-dimensional prototypes of articles have been fabricated by applying a layer of build material to a base, and then applying a binding liquid to the build material to bind the build material, with the two steps being repeated until the article has been completed. However, such a technique may often be hampered by the binding liquid's somewhat uneven absorption by the build material as well as uneven application of the binding liquid due to mechanical application inefficiencies. When binding liquid is not applied to a portion of the build material, that portion is structurally weak. When the article fabricated by the build material-binding liquid process is completed, such an article may readily break or crumble in the area in which binding liquid was not applied. Also, where the binding liquid is not evenly absorbed or is unevenly applied, distortion may occur in the fabricated article.
In conventional stereolithography technology, a liquid layer of a photopolymer composition is hardened using a laser beam that scans the surface of the photopolymer composition in a special three-dimensional reservoir. Layers of liquid photopolymer are hardened in the reservoir by scanning a focused laser in a predetermined three-dimensional pattern. This method requires a special reservoir. In addition, the use of a single point source, the laser beam, for hardening the photopolymer is inefficient and may not effectively harden all of the photopolymer, producing an object that has weakened areas.
Thus, there is a need for a method and apparatus that provide for efficiently binding build material to fabricate articles.